Condensed consolidated interim financial statements Condensed consolidaed interim financial statements (Policies)	3 Months Ended
Mar. 31, 2022
Accounting Policies [Abstract]
Condensed consolidated interim financial statements	The unaudited condensed consolidated interim financial statements included in this report are prepared by the Company. In the opinion of management, all adjustments necessary for a fair presentation of the results of operations are reflected in these condensed consolidated interim financial statements. All significant intercompany accounts and transactions have been eliminated. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of revenues, expenses, assets, liabilities, contingencies and noncontrolling interests subject to put provisions. The most significant estimates and assumptions underlying these financial statements and accompanying notes generally involve revenue recognition and accounts receivable, certain fair value estimates, accounting for income taxes and loss contingencies. The results of operations reflected in these interim financial statements may not necessarily be indicative of annual operating results. These condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 (2021 10-K). Prior period classifications conform to the current period presentation. The Company has evaluated subsequent events through the date these condensed consolidated interim financial statements were issued and has included all necessary adjustments and disclosures.
Revenue	There are significant uncertainties associated with estimating revenue, which generally take several years to resolve. These estimates are subject to ongoing insurance coverage changes, geographic coverage differences, differing interpretations of contract coverage and other payor issues, as well as patient issues, including determination of applicable primary and secondary coverage, changes in patient insurance coverage and coordination of benefits. As these estimates are refined over time, both positive and negative adjustments to revenue are recognized in the current period. Dialysis patient service revenues. Revenues are recognized based on the Company’s estimate of the transaction price the Company expects to collect as a result of satisfying its performance obligations. Dialysis patient service revenues are recognized in the period services are provided based on these estimates. Revenues consist primarily of payments from government and commercial health plans for dialysis services provided to patients. The Company maintains a usual and customary fee schedule for its dialysis treatments and related lab services; however, actual collectible revenue is normally recognized at a discount from the fee schedule. Other revenues. Other revenues consist of revenues earned by the Company's non-dialysis ancillary services as well as fees for management and administrative services to outpatient dialysis businesses that the Company does not consolidate. Other revenues are estimated in the period services are provided. The Company's U.S. ancillary service revenues include revenues earned under risk-based arrangements in the Company's integrated kidney care (IKC) business, including value-based care (VBC) arrangements. Under its VBC arrangements, the Company assumes full or shared financial risk for the total medical cost of care for patients below or above a benchmark. The benchmarks against which the Company incurs profit or loss on these contracts are typically based on the underlying premiums paid to the insuring entity (our counterparty), with adjustments where applicable, or on trended or adjusted medical cost targets.
Earnings Per Share	Basic earnings per share is calculated by dividing net income attributable to the Company by the weighted average number of common shares outstanding. Weighted average common shares outstanding include restricted stock unit awards that are no longer subject to forfeiture because the recipients have satisfied either the explicit vesting terms or retirement eligibility requirements. Diluted earnings per share includes the dilutive effect of outstanding stock-settled stock appreciation rights and unvested stock units as computed under the treasury stock method.
Short-term and Long-term Investments	Debt securities: The Company's short-term debt investments are principally bank certificates of deposit with contractual maturities longer than three months but shorter than one year. These debt securities are accounted for as held-to-maturity and recorded at amortized cost, which approximated their fair values at March 31, 2022 and December 31, 2021.Equity securities: The Company holds certain equity investments that have a readily determinable fair value from public markets. The Company's remaining short-term and long-term equity investments are held within a trust to fund existing obligations associated with the Company’s non-qualified deferred compensation plans.
Long-term debt	These cap agreements are designated as cash flow hedges and, as a result, changes in the fair values of the cap agreements are reported in other comprehensive income. The original premiums paid for the caps are amortized to debt expense on a straight-line basis over the term of each cap agreement starting from its effective date.
Fair Value of Financial Instruments	Interest rate cap agreements are recorded at fair value estimated from valuation models utilizing the income approach and commonly accepted valuation techniques that use inputs from closing prices for similar assets and liabilities in active markets as well as other relevant observable market inputs at quoted intervals such as current interest rates, forward yield curves, implied volatility and credit default swap pricing. The Company does not believe the ultimate amount that could be realized upon settlement of these interest rate cap agreements would be materially different from the fair value estimates currently reported. See Note 6 for further discussion.The estimated fair value measurements of contingent earn-out obligations are primarily based on unobservable inputs, including projected earnings before interest, taxes, depreciation, and amortization (EBITDA), revenue and certain operating metrics. The estimated fair values of these contingent earn-out obligations are remeasured as of each reporting date and could fluctuate based upon any significant changes in key assumptions, such as changes in the Company's credit risk adjusted rate that is used to discount obligations to present value.
New Accounting Standards	New accounting standards New standards not yet adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASU No. 2020-04 provides optional expedients and exceptions for applying U.S. generally accepted accounting principles to contract modifications and hedging relationships, subject to certain criteria, that reference LIBOR or another rate that is expected to be discontinued. The amendments in this ASU were effective beginning on March 12, 2020, and the Company may elect to apply the amendments prospectively through December 31, 2022. Effective January 1, 2022 certain LIBOR tenors that do not affect the Company, including the one-week and two-month U.S. dollar LIBOR rate, ceased or became non-representative. The remaining U.S. dollar LIBOR tenors will cease or become non-representative effective July 1, 2023. This change will have no impact on the Company's ability to borrow. The Company is currently assessing the other effects this guidance may have on its consolidated financial statements. In October 2021, the FASB issued ASU No. 2021-08, Business Combinations (Topic 805): Accounting for Acquired Contract Assets and Contract Liabilities. ASU 2021-08 requires application of ASC 606, Revenue from Contracts with Customers, to recognize and measure assets and liabilities from contracts with customers acquired in a business combination. This ASU creates an exception to the general recognition and measurement principle in ASC 805 and will result in recognition of contract assets and contract liabilities consistent with those recorded by the acquiree immediately before the acquisition date. ASU 2021-08 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted for all entities. The Company is currently assessing the effect this guidance may have on its consolidated financial statements.

Condensed consolidated interim financial statements Condensed consolidaed interim financial statements (Policies)

3 Months Ended

Mar. 31, 2022

Condensed consolidated interim financial statements

The unaudited condensed consolidated interim financial statements included in this report are prepared by the Company. In the opinion of management, all adjustments necessary for a fair presentation of the results of operations are reflected in these condensed consolidated interim financial statements. All significant intercompany accounts and transactions have been eliminated. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of revenues, expenses, assets, liabilities, contingencies and noncontrolling interests subject to put provisions. The most significant estimates and assumptions underlying these financial statements and accompanying notes generally involve revenue recognition and accounts receivable, certain fair value estimates, accounting for income taxes and loss contingencies. The results of operations reflected in these interim financial statements may not necessarily be indicative of annual operating results. These condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 (2021 10-K). Prior period classifications conform to the current period presentation. The Company has evaluated subsequent events through the date these condensed consolidated interim financial statements were issued and has included all necessary adjustments and disclosures.

Revenue

There are significant uncertainties associated with estimating revenue, which generally take several years to resolve. These estimates are subject to ongoing insurance coverage changes, geographic coverage differences, differing interpretations of contract coverage and other payor issues, as well as patient issues, including determination of applicable primary and secondary coverage, changes in patient insurance coverage and coordination of benefits. As these estimates are refined over time, both positive and negative adjustments to revenue are recognized in the current period.

Dialysis patient service revenues. Revenues are recognized based on the Company’s estimate of the transaction price the Company expects to collect as a result of satisfying its performance obligations. Dialysis patient service revenues are recognized in the period services are provided based on these estimates. Revenues consist primarily of payments from government and commercial health plans for dialysis services provided to patients. The Company maintains a usual and customary fee schedule for its dialysis treatments and related lab services; however, actual collectible revenue is normally recognized at a discount from the fee schedule.

Other revenues. Other revenues consist of revenues earned by the Company's non-dialysis ancillary services as well as fees for management and administrative services to outpatient dialysis businesses that the Company does not consolidate. Other revenues are estimated in the period services are provided. The Company's U.S. ancillary service revenues include revenues earned under risk-based arrangements in the Company's integrated kidney care (IKC) business, including value-based care (VBC) arrangements. Under its VBC arrangements, the Company assumes full or shared financial risk for the total medical cost of care for patients below or above a benchmark. The benchmarks against which the Company incurs profit or loss on these contracts are typically based on the underlying premiums paid to the insuring entity (our counterparty), with adjustments where applicable, or on trended or adjusted medical cost targets.

Earnings Per Share

Basic earnings per share is calculated by dividing net income attributable to the Company by the weighted average number of common shares outstanding. Weighted average common shares outstanding include restricted stock unit awards that are no longer subject to forfeiture because the recipients have satisfied either the explicit vesting terms or retirement eligibility requirements.

Diluted earnings per share includes the dilutive effect of outstanding stock-settled stock appreciation rights and unvested stock units as computed under the treasury stock method.

Short-term and Long-term Investments

Debt securities: The Company's short-term debt investments are principally bank certificates of deposit with contractual maturities longer than three months but shorter than one year. These debt securities are accounted for as held-to-maturity and recorded at amortized cost, which approximated their fair values at March 31, 2022 and December 31, 2021.Equity securities: The Company holds certain equity investments that have a readily determinable fair value from public markets. The Company's remaining short-term and long-term equity investments are held within a trust to fund existing obligations associated with the Company’s non-qualified deferred compensation plans.

Long-term debt

These cap agreements are designated as cash flow hedges and, as a result, changes in the fair values of the cap agreements are reported in other comprehensive income. The original premiums paid for the caps are amortized to debt expense on a straight-line basis over the term of each cap agreement starting from its effective date.

Fair Value of Financial Instruments

Interest rate cap agreements are recorded at fair value estimated from valuation models utilizing the income approach and commonly accepted valuation techniques that use inputs from closing prices for similar assets and liabilities in active markets as well as other relevant observable market inputs at quoted intervals such as current interest rates, forward yield curves, implied volatility and credit default swap pricing. The Company does not believe the ultimate amount that could be realized upon settlement of these interest rate cap agreements would be materially different from the fair value estimates currently reported. See Note 6 for further discussion.The estimated fair value measurements of contingent earn-out obligations are primarily based on unobservable inputs, including projected earnings before interest, taxes, depreciation, and amortization (EBITDA), revenue and certain operating metrics. The estimated fair values of these contingent earn-out obligations are remeasured as of each reporting date and could fluctuate based upon any significant changes in key assumptions, such as changes in the Company's credit risk adjusted rate that is used to discount obligations to present value.

New Accounting Standards

New accounting standards

New standards not yet adopted

In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASU No. 2020-04 provides optional expedients and exceptions for applying U.S. generally accepted accounting principles to contract modifications and hedging relationships, subject to certain criteria, that reference LIBOR or another rate that is expected to be discontinued. The amendments in this ASU were effective beginning on March 12, 2020, and the Company may elect to apply the amendments prospectively through December 31, 2022. Effective January 1, 2022 certain LIBOR tenors that do not affect the Company, including the one-week and two-month U.S. dollar LIBOR rate, ceased or became non-representative. The remaining U.S. dollar LIBOR tenors will cease or become non-representative effective July 1, 2023. This change will have no impact on the Company's ability to borrow. The Company is currently assessing the other effects this guidance may have on its consolidated financial statements.

In October 2021, the FASB issued ASU No. 2021-08, Business Combinations (Topic 805): Accounting for Acquired Contract Assets and Contract Liabilities. ASU 2021-08 requires application of ASC 606, Revenue from Contracts with Customers, to recognize and measure assets and liabilities from contracts with customers acquired in a business combination. This ASU creates an exception to the general recognition and measurement principle in ASC 805 and will result in recognition of contract assets and contract liabilities consistent with those recorded by the acquiree immediately before the acquisition date. ASU 2021-08 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted for all entities. The Company is currently assessing the effect this guidance may have on its consolidated financial statements.